Reduction in Circulating Microplastics in Humans Following Gastrointestinal Sequestration by Chitosan: A Pilot Controlled Study

Microplastics (MPs) are emerging contaminants that have been detected in human blood and tissues, raising concerns regarding systemic exposure and potential health effects. Internal MP burden mitigation techniques, nevertheless, are yet largely unexplored. We evaluated whether oral administration of chitosan derived from Procambarus clarkii (PCC) could reduce circulating MPs in humans via gastrointestinal sequestration in this pilot-controlled study. 11 healthy adults received PCC supplementation (0.8 g/day) for 15 days, while 10 matched controls received a placebo. Using stereomicroscopy, scanning electron microscopy (SEM), and micro-Fourier transform infrared spectroscopy (µFTIR), blood MP concentrations were quantified and characterised according to size, shape, and polymer type. At baseline, MPs were found in every subject. Following PCC supplementation, mean MP concentrations decreased from 1.84 ± 0.28 µg/mL to 1.34 ± 0.20 µg/mL (−26.3%, p < 0.01, paired analysis). The control group observed no significant differences. While polymer-resolved analysis consistently indicated reductions across major polymer classes, size-resolved analysis indicated preferential reductions in intermediate particle fractions (11–50 µm). The circulating MPs’ estimated mean residence time (MRT) was 58 ± 28 days. These findings provide preliminary evidence that chitosan-based gastrointestinal sequestration could potentially reduce the systemic MP burden in humans.